Tulip first, congratulations on the house! Excellent advice here - especially about adding 20% to your budget and doubling the timeline. I have extensively remodeled sections of my house (not a bungalo, but a brick rancher - the LAST thing I wanted when I was house shopping! - go figure). My goal when I bought the house was to make it as energy-efficient as possible.

I knocked out walls and remodeled the kitchen. Am now in the middle of knocking out more walls and turning the attached garage into a great room (incorporating the kitchen).

I replaced the ancient hardly-working heat pump with a gas furnace/heat pump combo. The heat pump has an external thermostat and when the temperature dips below 40 (about the limit of a heat pump's efficiency) the gas furnace comes on. It is extremely efficient and our heating bills dropped immediately. I keep the thermostat low in the winter as well so that helps & I only use the A/C when it gets really hot. Ceiling fans in every room help keep things cool.

I don't have a whole-house fan but do have a thermostatically controlled attic fan. I have not replaced it - it came with the house but still works fine.

The house had two wood-burning fireplaces and a third flue in the basement with a wood stove. The first couple winters we heated exclusively with the wood stove. The work & the mess finally got to us and we took it out and closed the flue. We closed the flues in both the living room and the kitchen fireplaces and installed a gas log in the kitchen fireplace. It heats the house if the electricity goes off. Eventually I will do the same in the living room. Be wary of wood-burning fireplaces. The fire is wonderful but the chimney sucks more heat up and out than it puts into the room - unless you have an insert & a blower.

My laundry is in the basement, too. I installed a front-loading washer and a new dryer & have been very happy with them. That is about the extent of what I have done in the basement.....replacing the water heater with an on-demand is on the list, as is remodeling the bedroom/bathroom down there. Someday I will get to it - I will never run out of projects!

You mentioned having to go outside to get to the basement. Would there be room somewhere to tuck a set of stairs in so that you would not have to do that?

Good luck & post before and after pictures once you get started!